1. Field of the Invention
The present invention is generally related to a fuel system for a marine propulsion system and, more particularly, to a fuel system that provides a fuel reservoir in which two pumps, a lift pump and a high pressure pump, are housed and disposed within a volume of fuel stored in the fuel reservoir.
2. Description of the Prior Art
Many different types of fuel delivery systems are known to those skilled in the art for use with marine propulsion systems. Certain fuel delivery systems incorporate fuel vapor separators, which act as a reservoir and a mechanism for separating fuel vapor from liquid fuel.
U.S. Pat. No. 5,819,711, which issued to Motose on Oct. 13, 1998, describes a vapor separator for a fuel injected engine. The fuel injection system of an engine, and particularly an outboard motor, includes a fuel vapor separator that is disposed on one side of the throttle bodies at the front of the engine. The fuel vapor separator is comprised of a housing assembly having a cover plate in which an integral fuel inlet fitting, an integral fuel outlet fitting, an integral vent fitting and an integral fuel return fitting are formed. The fuel injectors for the engine are disposed on the opposite side of the throttle bodies from the fuel vapor separator and are supplied with fuel through a vertically extending fuel rail. The pressure regulator is positioned at the top of the fuel rail and the fuel rail is directly affixed to the throttle bodies.
U.S. Pat. No. 5,375,578 which issued to Kato et al on Dec. 27, 1994, describes a high pressure fuel feeding device for a fuel injection engine. The injection system for an outboard motor includes a vapor fuel separator that has a fuel chamber in which the supply of fuel is maintained by a float valve and an air chamber positioned above the fuel chamber and to one side of it and which communicates with the fuel chamber through a perforated member. A fuel media fills the air chamber and an atmospheric air inlet is provided to the air chamber. Fuel pressure and fuel regulator valves are disposed in the area to the side of the air chamber and regulate fuel and air pressure by dumping fuel and air back to the fuel and air chambers, respectively, through integral internal conduits. The regulating system includes an arrangement for regulating the fuel pressure so that it will be at least greater than the air pressure by a predetermined amount and also for precluding the delivery of air under pressure if fuel under pressure is not supplied.
U.S. Pat. No. 5,579,740, which issued to Cotton et al on Dec. 3, 1996, describes a fuel handling system. The system is intended for use with an internal combustion engine having a vapor separator for receiving fuel from a remote tank and a pump for delivering the fuel under high pressure to a fuel injector of the engine while providing vapor separation. The separator has an inlet for receiving fuel from the tank, an outlet for enabling fuel to be removed and delivered to the engine, at least one return for enabling fuel not used by the engine to be returned to the separator, and a vent for removing fuel vapor from a gas dome above a pool of liquid fuel within the separator. The inlet has a valve controlled by a float in the reservoir for admitting fuel to maintain the level of liquid fuel in the separator. To retard foaming and excessive vaporization of liquid fuel in the separator, the separator has a perforate baffle between any return and the liquid fuel pool.
U.S. Pat. No. 5,404,858, which issued to Kato on Apr. 11, 1995, describes a high pressure fuel feeding device for a fuel injection engine. An outboard motor is provided with a fuel injection system in which all of the major components of the fuel portion of the fuel/air injection system are contained within a sealed chamber having a fuel drain and the conduits that supply fuel to the fuel injectors are also contained within the fuel collecting conduits so that any fuel leaking will not escape to the atmosphere. In addition, the air pressure supplied to the fuel/air injectors is regulated and the air relieved for pressure regulation is returned to an air inlet device having a baffle for condensing any fuel in the regulated air and returning the condensed fuel to a vapor separator.
U.S. Pat. No. 5,389,245, which issued to Jaeger et al on Feb. 14, 1995, discloses a vapor separating unit for a fuel system. The vapor separating unit has particular application to a fuel system for a marine engine. The vapor separating unit includes a closed tank having a fuel inlet through which fuel is fed to the tank by a diaphragm pump. The liquid level in the tank is controlled by float-operated valve. An electric pump is located within the vapor separating tank and has an inlet disposed in the tank and an outlet connected to a fuel rail assembly of the engine. Excess fuel from the fuel rail assembly is conducted back to the upper end of the vapor separator tank. A vapor venting mechanism is incorporated in the tank to vent vapor from the tank.
U.S. Pat. No. 5,368,001, which issued to Roche on Nov. 29, 1994, describes a fuel handling system for an internal combustion engine which has a reservoir for receiving fuel under low pressure from a remote gas tank and a fuel pump for delivering the fuel under high pressure to a fuel injector of the engine while providing vapor separation. The reservoir has an inlet for receiving fuel from the tank, an outlet for removing fuel from the reservoir and delivering it to the engine, a fuel return for returning fuel not used by the engine, a drain for removing water, and a vapor vent for removing fuel vapors from a gas dome above the liquid within the reservoir. The inlet has a valve controlled by a float in the reservoir for admitting fuel to maintain the level of liquid in the reservoir so that the pump is supplied with fuel. To remove fuel, a fuel pickup is coupled to an inlet of the pump which has its outlet coupled to the reservoir outlet. The pickup has a diaphragm for filtering fuel entering the pump while preferably preventing the admission of gas or water. Preferably, a water sensor in the reservoir provides an electrical signal when it is immersed in water so that the drain can be opened to remove the water, preferably before the pickup is immersed and fuel flow to the pump and engine is cut off.
U.S. Pat. No. 5,103,793, which issued to Riese et al on Apr. 14, 1992, discloses a vapor separator for an internal combustion engine. The vapor separator includes a bowl member and a cover member. A fuel pump is located in the internal cavity of the bowl member and has its inlet located in the lower portion of the bowl member cavity, for supplying fuel thereto. The fuel pump is secured in position within the bowl member by engagement of the cover member with the fuel pump. The cover member includes a mounting portion for mounting a water separating filter element to the vapor separator assembly. The cover member includes structure for routing fuel from the discharge of the water separating filter element to the interior of the bowl member internal cavity. A compact arrangement is thus provided for the vapor separator, the fuel pump, and the water separating filter, eliminating a number of hose connections between such components as well as facilitating assembly of the engine.
U.S. Pat. No. 5,309, 885, which issued to Rawlings et al on May 10, 1994, describes a marine propulsion device including a fuel injected, four-cycle internal combustion engine. The internal combustion engine comprises an engine block including a combustion chamber, a fuel vapor separator, a fuel supply mechanism for introducing fuel to the combustion chamber, a conduit communicating between the fuel vapor separator and the fuel supply mechanism for introducing fuel, and a cooling jacket for cooling the fuel vapor separator.
U.S. Pat. No. 6,170,470 B1, which issued to Clarkson et al on Jan. 9, 2001, discloses a fuel supply system for an internal combustion engine. The fuel system provides first and second conduits that draw fuel from first and second positions, or locations, within a fuel reservoir. If water exists in the fuel reservoir, the second position is selected to be lower in the fuel reservoir than the first position so that accumulated water will be drawn through the second conduit under certain conditions, such as when the engine is operating at a speed above the minimum threshold. The fuel reservoir can be a fuel tank or auxiliary fuel tank of a vehicle or watercraft or, alternatively, it can be the housing of a fuel/water separator.
U.S. patent application Ser. No. 09/550,720 which was filed by Wickman et al on Apr. 17, 2000 and assigned to the assignee of the present application, discloses a fuel supply method for a marine propulsion engine. The method for controlling the operation of a fuel system of an outboard motor uses a lift pump to transfer fuel from a remote tank to a vapor separator tank. Only one level sensor is provided in the vapor separator tank and an engine control unit monitors the total fuel usage subsequent to the most recent filling of the tank. When the fuel usage indicates that the fuel level in the vapor separator tank has reached a predefined lower level, a lift pump is activated to draw fuel from a remote tank and provide that fuel to the vapor separator tank.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
In marine propulsion systems, and particularly in outboard motors, it is advantageous if components can be packaged in a way that reduces the required volume for the assembly of components. It is also advantageous if the components of a fuel delivery system for a marine propulsion system can be cooled in a way that prevents the vaporization of liquid fuel in response to heat being transmitted to the fuel components.
A fuel system for a marine propulsion system, made in accordance with the preferred embodiment of the present invention, comprises a reservoir having a cavity for containing liquid fuel for use by the marine propulsion system. It also comprises a first pump for drawing fuel from a fuel supply and pumping the fuel at a first pressure magnitude into the cavity. The first pump is disposed within the cavity and in thermal communication with the liquid fuel. The present invention further comprises a second pump for drawing the fuel from the cavity and pumping the fuel at a second pressure magnitude to an engine of the marine propulsion system. The second pump is disposed within the cavity and in thermal communication with the liquid fuel.
The present invention, in a preferred embodiment, further comprises a fuel tank that is connected as a fuel supply to an inlet of the first pump. A fuel filter is connected in fluid communication between the first tank and the first pump. The fuel filter can be a water separating fuel filter.
In certain embodiments of the present invention used in conjunction with fuel injected engines, the present invention further comprises a fuel rail connected in fluid communication with an outlet of the second pump. The fuel rail is connected in fluid communication with a plurality of fuel injectors which inject fuel either into a intake manifold of the engine or, in direct fuel injected (DFI) engines, directly into the combustion chambers of the engines.
A preferred embodiment of the present invention further comprises a fuel return line connected in fluid communication between an outlet of the fuel rail and the reservoir. A preferred embodiment of the present invention further comprises a pressure regulator connected between the outlet of the fuel rail and the reservoir in order to maintain a preselected pressure within the fuel rail. The pressure regulator is connected in fluid communication with an air intake manifold of the marine propulsion system in order to provide a reference pressure for the regulator. The preselected pressure within the fuel rail can be a preselected differential pressure magnitude above an air pressure within the air intake manifold of the engine.
The present invention can also comprise a fuel level sensor disposed within the reservoir to detect a fuel level within the reservoir. An engine control module (ECM) can be connected in signal communication with the first pump and in signal communication with the fuel reservoir, in order to turn the first pump on and off as a function of the level of liquid fuel within the reservoir.
In a preferred embodiment of the present invention, the first pressure magnitude is less than the second pressure magnitude and the marine propulsion system is an outboard motor. The reservoir, in one alternative embodiment of the present invention, is attached for support to a driveshaft housing of the outboard motor and, as a result of this location, the reservoir is at least partially submerged in water when a propeller of the marine propulsion system is not rotating.